高斯光束斜入射非平行法布里-珀罗干涉仪后的透射光强分布

基于多光束干涉原理,推导出了高斯光束斜入射非平行法布里-珀罗干涉仪射后的透射光强表达式,在此基础上,着重研究了高斯光束入射角的大小以及法布里-珀罗干涉仪两反射端面的不平行度对透射光强分布的影响。研究结果表明：入射角的大小和干涉仪的不平行度对透射光的强度分布、峰值强度的大小和峰值强度的位置有很大的影响;在入射高斯光束具有较小的腰斑半径或法布里-珀罗干涉仪的两端面的反射率较大时,必须考虑高斯光束沿传输轴线的衍射效应;楔角为负的非平行法布里珀罗出射光斑的光强在“反跳”处急剧下降到零,可利用这一特点对距离进行精确测量。     

倾斜入射楔形薄膜滤光片的透射光谱研究

角度调谐薄膜滤光片因较大的波长调谐特性和良好的矩形度在密集波分复用系统中得到了广泛的应用。在倾斜入射时薄膜滤光片透射光谱的透射率和半宽不仅受到入射角度的影响,还跟滤光片两端面间的非平行度即楔角的大小有关。详细分析了楔角对对滤光片透射率以及半宽的影响,发现适当的楔角和角度取向能够改善倾斜入射状态下滤光片的透射光谱特性。设计制备了楔角为0.8°的楔形薄膜角度调谐滤光片,实验结果证明保持该楔角的方向与倾斜入射角度相同时会严重的劣化透射光谱的透射率和矩形度,方向相反时则可以提高光谱的透射率以及矩形度,并使器件的波长调谐范围增大约10 nm。     

高斯光束斜入射窄带滤光片的透射光强分布

基于多光束干涉原理,推导了高斯光束斜入射角度调谐窄带滤光片后的透射光强表达式.在此基础上研究了入射角对高斯光束的透射特性的影响.计算和实验结果表明：随着入射角的增大,透射光强的光斑会出现一定程度的展宽现象|当入射角度较小时,输出为单一光斑,但其光强峰值位置产生了一定的偏移,并不在呈现高斯分布|当入射角度较大时,输出则为一系列的离散光斑.     

高斯光束斜入射窄带滤光片的透射光强分布

基于多光束干涉原理,推导了高斯光束斜入射角度调谐窄带滤光片后的透射光强表达式.在此基础上研究了入射角对高斯光束的透射特性的影响.计算和实验结果表明:随着入射角的增大,透射光强的光斑会出现一定程度的展宽现象;当入射角度较小时,输出为单一光斑,但其光强峰值位置产生了一定的偏移,并不在呈现高斯分布;当入射角度较大时,输出则为一系列的离散光斑.     

马普-赫斯棱镜对单模高斯光束光强分布影响分析

根据光在马普－赫斯棱镜两空气隙胶合层中的干涉效应,分析了其对单模高斯光束光强分布的影响.结果表明,对于某一高斯光束入射棱镜时,透射光束光强将随入射角的变化而呈现周期性的振荡;对于正入射的光束,当空气隙的厚度一定时,透射光强随棱镜两空气隙结构角的变化作周期性振荡;当结构角一定时,透射光强随空气隙厚度的变化作周期性变化;且透射高斯光束的形状也随棱镜结构的改变发生变化,表明,可以通过选择合适的棱镜结构以减小棱镜对透射光束的影响,对于成品棱镜,则可通过改变入射角使棱镜的性能达到较佳状态.     

格兰-泰勒棱镜空气隙厚度的测量

为了测量格兰一泰勒棱镜空气隙的厚度,分析了棱镜对单模高斯光束的影响.结果表明.经过棱镜后的透射光强随着光束在棱镜端面上的入射角变化呈现周期性的振荡,且振荡特性与入射光的波长,光强分布特性、棱镜结构角及宅气隙的厚度有关.对于给定波长的入射单模高斯光束,由于棱镜的结构角在棱镜胶合之前可以精确测得,所以通过分析这种振荡特性便町以得出棱镜空气隙的厚度.据此设计实验.测出了透射光强随入射角的周期性变化关系.利用计算机编程.間隔改变0.0001 mm作为理论计算中的空气隙厚度的取值.计算实验测得的透射光强振荡周期与理论计算值的相对偏差的平均值,对于样品棱镜,当该值为4.35%时取值最小,此时对应的空气隙厚度为0.0143 mm.     

Wollaston式平行分束偏光棱镜的光学特性分析EI北大核心CSCD

根据折射定律结合棱镜的结构特点,推导出了Wollaston式平行分束偏光棱镜所对应的切割角应满足的关系．利用菲涅尔公式和薄膜的光强透射理论,推导出棱镜的光强透射比、光强分束比和两出射光束的平行度表达式．通过Matlab数值模拟,研究并实验测量了棱镜的光强透射比、光强分柬比和出射光平行度随入射角或入射波长的变化关系．结果表明：出射光束的平行度与实验结果符合得非常好,光强透射比规律与理论结果一致．Wollaston式平行分束偏光棱镜的光强透射比和光强分柬比随入射角有微小的起伏变化,当入射光束的入射角在-3°～3°的范围内入射或波长在（400～1100）nm范围内变化时,两光束之间的夹角不超过0．42°,平行度稳定性较好．     

楔角参量对角度调谐滤光片反射特性影响的光谱学研究

三端口可调谐滤波器是全光智能交换网络和密集波分复用系统中的核心器件。其反射端口的光谱特性,尤其是反射率和信道隔离度对于滤波器的性能至关重要。角度调谐滤光片因其良好的矩形度和温度稳定性被广泛应用于三端口可调谐滤波器的制备,其反射端口的光谱特性不仅与倾斜入射角度的大小有关,而且与其非平行端面间的楔角参量有关。文章详细分析了楔角参量对非平行角度调谐滤光片的反射率及半宽的影响,仿真计算了楔角参量在不同极性和大小条件下角度调谐滤光片的反射光谱特性,揭示了保持适当的楔角参量和方向性可以改善倾斜入射状态下滤光片的反射光谱特性。设计并制备了楔角为0.8°的楔形角度调谐滤光片,实验证明了当保持楔角方向与倾斜入射方向相同时会严重的劣化透反射光谱的半宽和隔离度,方向相反时则可以改善反射光谱的反射率和半宽指标。通过负楔角参量的引入使得角度调谐滤光片较之高平行度的同类器件具有更高的反射率和信道隔离度。     

高斯光束斜入射法布里-珀罗干涉腔后的反射光强分布

基于多光束干涉原理,推导了高斯光束斜入射法布里-珀罗干涉仪后的反射光强表达式.在此基础之上数值研究了入射角对高斯光束的反射特性的影响.研究结果表明:当法布里-珀罗干涉腔的腔长满足反共振时,随着入射角的增大,反射光的光强分散,峰值强度下降后呈现出幅度衰减的波动;峰值位置随着入射角的增大,呈现出幅度越来越小的振荡偏移;光斑大小随入射角的增大,呈现出幅度减小的振荡.     

角度调谐滤光片准直系统发散角抑制技术研究

入射光束的发散角会影响角度调谐窄带滤光片的透射特性,出现透射通带变小及发散损耗增大的情况,且该现象随着入射角度的增大而更加明显.分析了出现这些现象的原因,并根据拉赫不变量定理设计了扩束棱镜组来压缩入射光束的发散角.并利用二次滤波技术进一步提高了透射光谱的矩形度和稳定性.根据该方法设计了针对100 GHz密集波分复用系统...     

Thin-film spatial filters

A thin-film optical filter used as a one-dimensional spatial filter is presented, and its design is briefly examined. The filter consists of a stack of quarter-wave dielectric layers upon a right-angle prism that selectively cancel a reflected or transmitted plane-wave front for various angles of incidence. Transmittance and reflectance are low-pass functions or high-pass functions of the angle of incidence with a high degree of steepness. In combination, these filters exhibit bandpass transmittance with a variable bandwidth. Applications to detection of extrasolar planets are briefly discussed.     

薄膜法布里-珀罗滤光片中反射高斯光束分裂现象

提出了一种模拟薄膜法布里-珀罗滤光片中反射光束分裂现象的方法.根据反射率曲线，简单解释了产生这个现象的原因.实验上制备了薄膜法布里-珀罗滤光片，观察和测量了反射光束分裂的现象，理论计算基本与实验结果符合. 关键词： 薄膜 法布里-珀罗 光束分裂     

A thin-film prism as a beam separator for multimode guided waves in integrated optics

We discuss a new application of a thin-film prism as a beam separator for multimode guided waves in integrated optics. For each mode of propagation, the angle of deflection by the thin-film prism is different and each deflected beam can be processed subsequently. Deflection angles for different modes can be predicted by using the concept of effective index of refraction. The thickness and index of refraction of the guiding film are determined simultaneously by measuring the coupling angles of the laser beam and a simple graphical method. Calculated and observed angles of deflection are in good agreement. The thin-film prism is made by using preferential etching technique in order to obtain linear, well defined, tapered edges. Furthermore, silicon is used as the base material for possible future integration of optical and electronic components.     

Negative Goos-Hanchen Effect in Thin-Film Fabry-Perot Filter

We investigate the Goos-Hgnchen effect of a Gaussian light beam reflected by the thin-film Fabry-Perot filter. It is shown that the Goos-Hanchen shift can be either negative or positive, The Gaussian-beam analysis and stationary phase method are introduced to calculate the lateral shift between the incident beam and the reflected beam at different wavelengths and to analyse the Goos-Hgnchen effect in the thin-film Fabry-Perot filter, The effect of the incident beam diameter is also discussed,     

Study of the polarization profile in film ferroelectrics by the thermal square wave method

The possibility of using the thermal square wave method at single frequency for the analysis of the polarization distribution over the depth of a thin-film ferroelectric has been considered. The temperature distribution in a ferroelectric film-substrate system has been calculated. The method has been tested using tin thiohypodiphosphate films on aluminum substrates.     

Polarization-independent broadband terahertz chiral metamaterials on flexible substrate

A THz band-reject filter is designed based on chiral four-fold rotational symmetry metamaterial. This filter was fabricated by laser micro-lens array lithography and characterized by terahertz time-domain spectroscopy. The resonant frequencies at different twist angles are almost the same, which demonstrates the polarization independence of the structure. The electric field distribution is simulated to explain the physics mechanism behind the polarization independence. By stacking multiple metamaterial layers together, a THz broadband reject filter at a bandwidth of 0.461 THz is experimentally achieved.     

基于薄膜滤光片的新型可重构光分插复用器

研制了一种基于窄带薄膜滤光片的可重构的光分插复用器(ROADM).它由三个单芯光纤准直器、一对三端口光环形器、一对全反射镜和一片特别设计的角度调谐窄带多腔薄膜滤光片组成.通过步进电机的推动调制角度调谐滤光片的倾斜入射角度,从而实现了可选择波长上下路.对该可重构的光分插复用器进行了实验研究,并对该器件的串扰特性进行了详细的分析与计算.实验中得到的上下路信道隔离度大于34 dB,可调谐范围大于26nm,与理论计算结构相符.该种新型的ROADM具有结构简单、可调谐范围大、隔离度高、低偏振相关损耗、成本低等特点,可广泛应用于各种密集波分复用(DWDM)光网络.     

Double fusion filtering based multi-view face recognition

Two-dimensional (2D) face recognition by correlation is a key challenge of telecommunication and optical information processing. Although this issue has been the focus of intense research, its utilization still has some drawbacks especially when the face is in rotation. In this paper, we propose an alternative method based on a newly designed optical correlation filter which allows recognizing faces with different view angles. This filter called “Multi-View Binary Phase-Only Filter” is based on a double fusion of reference images allowing an optimisation of the use of the spatial-bandwidth product (SBWP) in the filter Fourier plane. The first fusion is performed in the image (space) domain, and the second one is conducted in the spectral domain. Simulations results with the Pointing Head Pose Image Database illustrate the performance of the designed correlation filter for multi-view face recognition.     

Free-space 1×2 wavelength-selective switches for wavelength-division multiplexing optical networks

A free-space 1 ×2 wavelength-selective switch （WSS） based on thin-film filter technology is proposed. The 1 × 2 WSS is fabricated with an electromagnetic actuator, a reflecton prism, a narrow-band thin-film filter, and three fiber collimators. The working principle and the configuration of WSS are illuminated. The experimental results indicate a fiber-to-fiber insertion loss ranging from 1.109 to 1.249 dB with 2-V voltage input, which satisfies the application of optical fiber communication.     

多级全通均衡器对介质薄膜滤波器进行色散补偿的探讨

讨论了介质薄膜滤波器的色散特点,并推导了单级全通滤波器的理论色散。比较理论色散曲线与实际测量色散曲线,两者吻合较好。但由于单级全通滤波器的色散带宽及斜率不能满足实际所需的色散补偿曲线,因此提出了多级全通滤波器,通过控制级连的单级全通滤波器的谐振波长及反射率,可以增大色散带宽,改善色散斜率,使之满足实用的要求。文中给出了四级全通滤波器的理论色散曲线。